package org.apache.solr.core;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.store.Directory;
import org.apache.lucene.store.MMapDirectory;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.common.util.NamedList;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;

/**
 * Directly provide MMapDirectory instead of relying on
 * {@link org.apache.lucene.store.FSDirectory#open}
 * 
 * Can set the following parameters:
 * <ul>
 * <li>unmap -- See
 * {@link org.apache.lucene.store.MMapDirectory#setUseUnmap(boolean)}</li>
 * <li>maxChunkSize -- The Max chunk size. See
 * {@link org.apache.lucene.store.MMapDirectory#setMaxChunkSize(int)}</li>
 * </ul>
 * 
 **/
public class MMapDirectoryFactory extends DirectoryFactory {
	private transient static Logger log = LoggerFactory
			.getLogger(MMapDirectoryFactory.class);
	boolean unmapHack;
	private int maxChunk;

	@Override
	public Directory open(String path) throws IOException {
		MMapDirectory mapDirectory = new MMapDirectory(new File(path));
		try {
			mapDirectory.setUseUnmap(unmapHack);
		} catch (Exception e) {
			log.warn(
					"Unmap not supported on this JVM, continuing on without setting unmap",
					e);
		}
		mapDirectory.setMaxChunkSize(maxChunk);
		return mapDirectory;
	}

	@Override
	public void init(NamedList args) {
		SolrParams params = SolrParams.toSolrParams(args);
		maxChunk = params
				.getInt("maxChunkSize", MMapDirectory.DEFAULT_MAX_BUFF);
		if (maxChunk <= 0) {
			throw new IllegalArgumentException(
					"maxChunk must be greater than 0");
		}
		unmapHack = params.getBool("unmap", true);
	}
}
